Description. The mechanisms underlying brain functions, such as perception, motor control, learning and memory, in health and disease result from the coordinated responses of neurons distributed across multiple brain regions. However, conventional electrode technologies have not scaled to capture this networked activity. Researchers are forced to compromise between low-resolution over large areas of the brain or fine resolution over very small areas. With more than 12 million neurons per square centimeter of brain surface, high resolution interfaces which conform and cover multiple cortical regions are needed to further our understanding to offer effective intervention in disease. This SBIR proposal aims to develop a highly-conformable, ultra-soft, and high-density cortical ACTI- ECOG electrode array with 96 contacts accessible from only 16 wires which can be scaled to a large surface area (up to 10 x 10 inches). The technology is arrayable and scalable to 384 or more channels in Phase 2 using a fully-implantable device. This high-resolution array will embed an active interface electronic micro-chip which is sealed in a water-tight miniaturized pin-grid package within the flexible array. The electrode array technology contacting the brain is ultra-soft, conformal, multi-layered, and resilient to repetitive mechanical strain in contrast to thin-film materials which are rigid and not conformable in two dimensions simultaneously. This powerful tool will advance the research capabilities of closed-loop sensory prostheses, seizure monitoring and brain-machine interfaces. This SBIR Phase 1 addresses significant challenges in (1) creating a multi-layered, high-surface area, high-density, soft and conformal electrode which is flexible in 3D over the surface of the brain, (2) creating a research grade electronics package to improve scalability, (3) designing a 16 lead wires interface using a conventional connector to access the 96-contact array. To achieve these goals we propose three specific aims. AIM 1 will focus on fabricating multi-layered and high-density passive electrodes using our conformal electrode process, performing mechanical stress testing, and in-vivo validation over 3-6 months. Aim 2 will develop a 96- channel, conformal and high-density ACTI-ECOG array for multiplexed stimulation and recording. Aim 3 will perform in-vivo validation of the multi-layered passive arrays and the 96-channel ACTI-ECOG platform for recording and stimulation in the auditory cortex. TEAM. Our Team includes Dr. Bryan McLaughlin (Micro-Leads) and Dr. Jonathan Viventi (Duke University), who both specialize in high-resolution electrode manufacturing and testing. MARKET. The market for the proposed device is targeted primarily at academic institutions, research institutions, pharmaceutical companies, and biomedical device companies seeking to perform brain research. Based upon interview and the global number of laboratories, we estimate the total research market size is approximately $2M/year for this type of device. Our envisioned product is a multiplexed lead for large animal models, which in Phase 2 will be connected with a wireless implantable device to access hundreds of neural contacts.